"Shortly after the evening rush hour
had passed its peak on Wednesday 18 November 1987 a fire of catastrophic
proportions in the King's Cross Underground station claimed the lives
of 30 people and injured many more. A further person was to die in
hospital making the final death toll 31."

These are some of the opening words of
the Investigation into the King's Cross Underground fire in London in
the UK.1 The investigation called 150 witnesses, took 12
months to publish its findings, ran to more than 250 pages and made no
less than 157 recommendations.

The fire started in the grease and detritus on
the running tracks of an escalator and spread to the escalator's wooden
skirting board. Although smoking was not allowed in underground
stations, it is thought that a match was the cause of the fire.

The escalator's wooden decking and
balustrades were preheated by the fire and, once ignited, the flames
spread up the escalator trench and caused a flashover in the ticket
hall. Evacuation of the lower levels of the station was underway at the
time of the flashover, though unfortunately the escape route taken was
up a separate set of escalators and through the ticket hall where the
flashover occurred.

The changes in fire safety on London Underground were wide ranging and included:

Replacement of wood on escalators with metal

New emergency and evacuation procedures

Increased familiarization for emergency services

New systems for the management and audit of safety

A range of training programs for all station staff

Improved communication systems

In addition, existing building fire
safety legislation was extended to cover underground stations.

The wider changes to fire safety were perhaps more subtle and far-reaching and included:

Fire dynamics and the trench effect

Reaction to fire and toxicity testing

Human behavior in fire

Fire safety management and safety culture

The probabilistic nature of fire

Awareness of the importance of fire
dynamics was increased, and in particular the trench effect was
discovered. When both balustrades and the floor of the escalator trench
became involved in the fire, the flames, in entraining air on the
up-hill side, lay down in the escalator trench. The trench effect was
initially identified by researchers applying a (then) relatively new
approach to fire modelling called Computational Fluid Dynamics. A
similar effect had been observed before and is illustrated in An Introduction to Fire Dynamics.2

There was also a greater awareness of the
importance of the reaction of fire of station and rolling stock linings
and materials. Consequently, existing standards were further developed
and continue to be enhanced, including standard test methods for
toxicity testing.

The importance of human behavior in fire was also
recognized. For example, some passengers did not act on instructions
from station staff because they did not perceive them to be
authoritative. This perception had developed during normal operation and
has important implications for the training of staff. Other passengers
responded to police officers who happened to be on the scene and used
their initiative, but had little or no knowledge of the station or its
emergency procedures.

Fire safety management, and in particular the
importance of a safety culture, gained greater recognition. After the
fire, there was a radically different approach to near-misses and
internal inquiries into accidents were undertaken.

There was also a wider appreciation of
the probabilistic nature of the risk of ignition and fire. London
Underground had operated for over 100 years without a similar fire
event, yet this did not necessarily mean that such a fire could not
occur. Subsequently, the legislation for railways now requires a safety
case informed by quantitative assessment of risk. The fire safety
legislation for existing buildings is now also based on an assessment of
risk.

Following the King's Cross fire, there have been major changes to fire
safety on underground transport systems. Just as significantly, there
have also been more subtle and far-reaching changes in the understanding
of fire safety, and this can only have helped improve safety over the
last 23 years and continues improving fire safety into the future.